Synchronous dynamo-electric machine.



S J. BAOHE-WHG. SYNGHRONOUS DYNAMO ELECTRIC MACHINE.

980, APPLICATION FILED 1113.3, 1910. Patented Jan 3,

2 B'HEIIT8SHEBT 1.

I iNVENTOR WITNESSES:

ATTORNEY J. BACHE-WIIG.

SYNGHRONOUS DYNAMO ELECTRIC MACHINE.

APPLICATION FILED FEB. a, 1910.

980,183. Patented Jan. 3, 1911.

2 SHEETS-SHEET 2 WiTNESS 46mg; 410 6. CEZW'M INVENTOR TTORNEY I ED. TATEs PATENT OFFICE-t 5 JENS shone-wire, or :anonw'ooi) PARK,

PENNSYLVANIA, ASSIGNOR 'ro wns'rmo- HOUSE ELECTBIZ? AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLV ANIA.

Specification of Letters Patent.

srncnnonocs DYNAMO-ELECTRIC MACHINE.

Patented Jan. 3, 1911 Application filed February 3, 1910. Serial No. 541,818.

To all whom it may concern:

Be it known that I, Jnns BACHE-WIIG, a subject of the King of Norway, and a resident of Edgewood Park, in,the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvementin Synchronous Dynamo El'ect'ric Machines, of which the followin is a specification.

, My invention re ates to dynamo-electric machines and particularly to synchronous alternating current machines.

The object ofmy invention is to provide simple, eifective and relatively inexpensive means for preventing hunting of the speed or oscillations of the current in synchronous current machines, and for enabling such machines to be readily started as non-synchronous or inductionmotors.

. same heretofore comprised low-resistance shortcircuited windings surroundin the whole,- or parts, of theextremities of t e field mag- .net polar projections, the said windings being the most etfective'wl en placed near the edges of the poles, where ,themagnetic'flux variation is usually the greatest.' If properly arranged, a short-,circuited winding upon the extremities of the field magnet polar projections may be utilized also in starting the winding upon the field ma tions constitutes the secon ary winding. In order that a relatively large starting torquemotor and bringing it' up to synchronous 3 bed; current, for that purpose, being appied to the armature winding, which temporarily serves as, the primary winding of an" induction motor of which the short-.ci'rcuited net polar pro ec may be obtainechthe short-circuite'd Second ary winding should, of course, be-of relatively high resistance. It will be noted,

therefore, that while, for the purpose of damping the oscillations of current, the short-circuited winding upon the polar proections should be of low resistance, for the purpose of obtaining a high starting torque when the machine is operating as alnonsynchronous motor, it should be of relatively high resistance. Instead of providingtwo windings, each adapted to its particular purpose, it is the object of the present invention to provide a single winding that shall be effective for both purposes;

The machine here illustrated comprises a field ma et core structure having aphirality o rounded by coils 3 constituting an exciting winding, the field structure, in the-present instance, being rotatable, and the polar pro-L ections 2 being secured, by means of dovetail projections 4*, to a central spider or supporting member 6. Adjacent to their peripheral faces, the polar projections 2 are provided with transverse slots in which conducting bars 7 are located, the bars bein secured, at their extremities, to segmenta conducting rings 8 to form closed-circuit windings for the ends of the polar projections. The rings 8 are preferably composed of copper or some other comparatively lowresistance material, though, for some'purposes, it may be found desirable to construct them .of high-resistance material.

'TSifnce the greatest-effectiveness in reventing hunting of the motor speed, an oscilla-,

tions,of;the current in the alternating ourlow resistance, "which areylocated near .1 the edgesf-of thej'p'olar, projections where the magnetic fiuxflvariation is greatest, thethree conducting bars-"which .are located nearest ctheedges jofthe' polar projections of themachin'e-here illustrated are composed of coppen or other suitable low-resistance material. The bars nearv the middle ortions of the polar faces are composed 0 steel or other relatively high-resistance material, and, while they have -some effect as dampers, when combined with the. conductors near the edges of the poles, their primary function is that of a closed-circuit secondary winding which permitsthe machine to be started and brought up to speed as: a non-synpolar'projections 2 that are surirentcircu'it-to which the motor is connected is afi'orded by s'hort-ciiicuited windings of v chronous induction motor. Since theeflective resistance of the secondary winding is dependentupon the resistances of both the co pper and the steel. conductors, which are parts thereof it is evident that the effective resistance of the Winding is greater than it would be if all of the conductors were composed of copper. Consequently, it is possible to obtain a relatively high starting torque. At the same time, the winding has substantially the same effectiveness as a damper that it would have if all of the conductors were composed of copper.

I claim as my invention:

1. A synchronous dynamo-electric machine comprising polar projections having transverse peripheral slots, and conducting bars located in the slots and constituting parts of a closed-circuit winding, the bars near the edges of the polar projections being of lower resistance than those near the centers thereof.

2. A synchronous. dynamo-electric machine comprising polar projections, and a plurality of conductors supported near the faces of the polar-projections and constituting parts of aclosed-circuit Winding, the conductors near the edges of the polar projections being of less resistance than those near the centers thereof.

3. In a synchronous dynamo-electric machine, the combination with polar projections, of a distributed closed-circuit winding for each of said projections comprising a plurality of transverse conductors, those near the edges of the polar projections being of less resistance than those at the centers thereof, and conductors joining the extremities of the transverse conductors.

4. A synchronous dynamo-electric machine comprising polar projections, a plurality of conducting bars supported near the faces of the polar projections, the bars near the edges of the pole pieces being of less resistance than those near the centers thereof, and relatively low-resistance conductors connecting the ends of the said bars.

In testimony whereof, I have hereunto subscribed my name this 27th day of ,Jan., 1910.

JENS BACHE-XVIIG.

Witnesses:

R. A. SIMPSON, B. B. HINES. 

